OK, I am confused.
I'm sitting down to design the pi-net input circuit for my 2 x 3-500z amp. I
started by looking at the circuit for a similar amplifier in the 1994 ARRL
handbook. They use iron powder toroids for the coils. For example, the 80
meter circuit has cin = 630-940 (adjustable) pf, cout = 820 pf, and the coil is
specified as 21t #20 on a T-50-2 toroid. Naturally, they don't give the
inductance, but according to the Amidon data sheet, 21 turns on a T50-2 is about
10 uh.
When I run the calculation (Q = 2.5, input impedance 57 ohms) I get cin = 1006,
cout = 984, and l = 2.2 uh. I think my inductance value is closer to being
right.
Is this just another bug in the handbook? Or is the bug in my personal
brainware?
73,
Vic, K2VCO
Fresno CA
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